Astronomy

Supermassive Black Hole Mauls, Shreds and Devours Unfortunate Star

Astronomers have seen an unprecedented "tidal disruption event" where a black hole in the center of a distant galaxy is thought to have ripped a star to sheds, taking 10 years to eat the stellar entrails.

To say that straying too close to a black hole is a bad idea would be a massive understatement.

The extreme warping of spacetime caused by the black hole's intense gravity creates powerful tides that will rip any stars and planets to shreds, but only before spaghettifying them into oblivion. Generally, though, if a star gets turned into Silly Putty by a black hole's tides, the suffering is a short-lived and explosive affair, where some of the star stuff gets consumed and the rest is ejected back out into space.

"We have witnessed a star's spectacular and prolonged demise," said Dacheng Lin from the University of New Hampshire in Durham, New Hampshire. "Dozens of tidal disruption events have been detected since the 1990s, but none that remained bright for nearly as long as this one."

By combining the observational power of three space telescopes - NASA's Chandra X-ray Observatory and Swift satellite, plus the European XMM-Newton - the drama has been seen unfolding in the center of a galaxy around 1.8 billion light-years away. Generating powerful X-rays, the tidal disruption event (TDE) - called XJ1500+0154 - has been telling astronomers the violent story of what happens when a star, roughly twice the mass of our sun, gets consumed by a supermassive black hole.

The event was first spotted by XMM-Newton July 23rd, 2005, and it reached peak brightness in a Chandra observation on June 5, 2008. Since then, the dimming X-ray emissions have been observed multiple times over the years, revealing a fascinating insight to how the most massive black holes consume matter and, perhaps, how they so quickly gained mass in the early universe.

"For most of the time we've been looking at this object, it has been growing rapidly," said James Guillochon, of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., in a statement. "This tells us something unusual - like a star twice as heavy as our sun - is being fed into the black hole."

By measuring the X-ray emissions, astronomers have been able to gauge how efficiently the black hole has been able to consume the blended stellar material collecting in the black hole's accretion disk. In this case, it appears the stellar material from this TDE is still being consumed and models suggest X-ray emissions from this particular event will continue to dim over the next few years.

"This event shows that black holes really can grow at extraordinarily high rates," said Stefanie Komossa of QianNan Normal University for Nationalities in Duyun City, China. "This may help understand how precocious black holes came to be."

One of the biggest unsolved quastions hanging over modern cosmology is the known existence of supermassive black holes in the dawn of our universe - how did they become so massive so quickly? This new research about a strange TDE and one black hole's eating habits may hold at least part of the answer.